This invention relates to storm chokes or safety valves and is more particularly concerned with well valves which open automatically when a submergible pump is actuated but which otherwise remain closed.
It is common practice to provide an oil well or the like with a device known as a storm choke or safety valve for blocking the path by which the well fluid may flow to the earth's surface when such flow is not desired. For example, it is well known to provide well safety or blow out control valves which may be operated by a wire line, by hydraulic or pneumatic pressure transmitted from the surface, or in response to well flow rate or pressure parameters to shut off the flow of well fluid to the surface when such flow would be undesirable or dangerous. Devices of this type tend to be complicated, expensive, unwieldy, and/or unreliable. It is known to employ various types of valves in conjunction with pumps, but in general, such devices are not suited for use as effective storm chokes in connection with submergible pumps.
U.S. Pat. No. 3,807,894 to O'Rourke, assigned to the assignee of the present invention, discloses and claims improved storm chokes which open automatically in response to the operation of an associated submergible pump and which are attached to or form part of the inlet or outlet housing of the pump. All of the choke parts are adjacent to the pump and not dependent upon connections to distant operators. The chokes are normally closed by biasing springs and remain firmly closed under bottom-hole pressure, but they are readily opened in response to differential pumping pressure or pressure applied from the earth's surface. Reference is made to the prior art cited in the O'Rourke patent, and in addition, to the following prior patents, which are typical of the prior art:
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